I loved it. I was tearing up throughout the show, but rolling my eyes (and tearing up lol) during the last several minutes when it took a religious turn.
I wondered why Walt, Michael and Mr. Eko weren't there but I was too impressed they brought back so many old timers I let it pass.

But.... the island was REAL. They were all (or not ALL if you consider the absences of Mr. Eko etc) stuck in a sort of limbo. I'm expecting a spin-off of sorts off of Hugo's and Ben's last words along the lines of: "You were a good number 2" to which Ben replied "But you were a great number 1."
That implies to me that time kept passing for who-know-how-long before we saw them all in Limbo.
And because of the wreckage at the very end, part of me thinks the plane Kate etc were on crashed.... but, because of the nature of some of the wreckage, perhaps it was just a flashback of the beginning.

All in all, I've been almost entirely pleased with the show and the ending.